Fluid apparatus



June 20, 1961 B. G. GARDINEER, JR 2,989,005

FLUID APPARATUS Filed May 28, 1958 FIG.3

INVENTOR BAYARD G.GARDINEER JR.

Y fM/a/M AGENT United States Patent Ofifice 2,989,005 FLUID APPARATUSBayard G. Gardineer, Jr., Peekskill, N.Y., assignor to InternationalBusiness Machines Corporation, New York, N.Y., a corporation of New YorkFiled May 28, 1958, Ser. No. 738,551

2 Claims. ('Cl. 103-161) This invention relates generally to fluidoperated apparatus and more specifically to improvements in thestructure of fluid pumps and motors wherein the pistons are arranged ina radial array.

An object of the present invention is to provide an improved structurefor radial type fluid pumps and motors so as to achieve a minimum momentof inertia in the rotating parts.

A further object is to provide an improved configuration of parts in theaforesaid apparatus so as to improve the life of the apparatus through areduction in wear. Yet another object to is provide in the aforesaidappa'ratus a fewer number of parts, each of which has a simpleeasily-fabricated shape so as to reduce the cost of the apparatus.

A final and specific object of the invention is to provide an improvedpiston and reaction ring structure for a radial piston type fluid pumpor motor for the achievement of the" aforementioned objects.

Other objects of the invention will be pointed out in the followingdescription and claims and illustrated in the accompanying drawings,which disclose, by way of example, the principle of the invention andthe best mode, which has been contemplated, of applying that principle.

FIG. 1 is a partial sectional view of the invention taken along the axisof rotation of the device.

FIG. 2 is a transverse sectional view through the rotor, taken along theline 2-2 of FIG. 1.

FIG. 3 is a geometric diagram of the piston travel.

FIG, 4 is a development of the reaction ring showing the wear pattern.

Prior art fluid motors or pumps of the radial piston typecharacteristically employ pistons radially disposed in a rotor havingcylinder bores which receive the pistons and provide expansible fluidchambers which are selectively connected to high and low pressurechambers by rotation of the rotor, whereby the radial movement of thepistons through coaction of the pistons witha reaction ring, which iseccentrically disposed with respect to the axis of rotation of therotor, either eifects apumping of the fluid, if external rotationalpower is applied to the rotor, or an auto-rotation of the rotor, ifexternal power in the form of a diiferential fluid pressure is appliedthereto. Whereas hydraulic devices have in the past found their'chiefutility in slow speed large force applications, their use in high speedapplications with rapid accelerations and reversals has required thatthe rotating parts of pumps and motors, particularly thelatter, bedesigned with a moment of inertia to permit of high acceleration as wellas be designed to have optimum wear characteristics, wear beingaccentuated by the high operating speeds.

The instant invention seeks to overcome the limitations of the prior artdevices by providing an improved piston and reaction ring structurewhereby the moment of inertia of the rotating parts is considerablyreduced, and the useful life of the parts is prolonged through reductionin wear. To this end, the pistons are formed at their outer end with aplanar cut oblique to the axis thereof so as to form a point contactwith the cylindrical inner surface of the reaction ring, the point ofcontact being eccentric with respect to the axis of the piston so as toprovide a sort of castoring action as the pistons move with re- PatentedJune 20, 1961 spect to the reaction ring, so as to distribute the wearover a larger area of the reaction ring.

The preferred construction of a fluid pump or motor embodying theinstant invention is shown in the drawings, the description of whichwill be confined to the use of the apparatus as a fluid motor forlucidity only. With reference to FIG. 1, fluid from an external sourceof high pressure is connected to either the conduit 10 or conduit 11,depending on the desired direction of rotation, which conduits connectrespectively with the chambers 12a and 125 (FIG. 2) formed internally ofthe tubular spindle 12 by a longitudinal barrier 120 which isolates thetwo chambers from one another. Communicating with the chambers 12a and12b and ports 12a, 122, 12 and 12g (not shown) which are so spaced bothaxially and radially that the fluid in the chambers 12a and 12b issuccessively connected to the cylindrical bores 13a to 13 inclusive,which bores are radially disposed in rotor '13 which rotates on thetubular spindle 12. Slideably mounted in the cylindrical bores 13a to 13in fluid confining relationship therewith are the pistons 14 through 21,and 24 through 31 (some of which are hidden in the drawings). Each ofthese pistons has a substantially cylindrical configuration except forthe outer surface thereof which, although planar, is obliquely disposedwith respect to the axis of piston so as to provide a single point orsmall area exemplified by 14a on the piston 14, which point iseccentrically located with respect to the axis of the piston and extendsaxially beyond any other portion of the piston. Although any surfaceconfiguration of the end of the pistons that satisfies the requirementthat the point of contact of the piston be oh. the axis of the piston issatisfactory, it has been found that the most practical shape is theplanar shape hereinabove described wherein the plane is inclined at anangle of 5 /2 degrees from the perpendicular to the axis where thediameter of the pistons is inches, the diameter of the reaction ring 2inches and the eccentricity between the reaction ring and the rotorcenter is .140 inch. The chief advantage of the planar shape oversimilar functioning configurations is its ease of fabrication andconsequent economy. Each of these points on the respective pistonsco-acts with a cylindrical inner race 32a of an anti-friction bearing32, which bearing is eccentrically disposed with respect to the axis ofrotation of rotor 13, the orientation of the eccentricity being sodisposed with respect to the chambers 12a and 12b and the ports 12d,12e, 121 and 12g that the pistons will be exposed to the high pressureconduit in their are of travel wherein the clearance between the rotor13 and the inner race 32a is increasing and to the low pressure conduitwhen the clearance is decreasing.

The rotor 13 is provided with a plurality of radial slots 13K whichengage with a complementarily shaped multi-forked clevis 33 for drivingconnection therewith. The clevis '33 includes an integral shaft 33awhich is journalled in bearings 34a and 34b and suitably sealed againstfluid leakage by seals 35a and 35b. A suitable casing 40 mounts andlocates the parts in their proper orientation and prevents the loss offluid from the appa-ratus.

The foregoing description has been somewhat abridged, and the drawingshave been simplified for purposes of simplicity. Usually fluid motors ofthis type employ an odd number of cylinders in any one circular array aswell as more than the two circular arrays shown. Such a showing, here,would produce asymmetrical sections and lengthy exposition which isunnecessary to an understanding of the invention.

Referring now to FIG. 2 it will be seen that during a clockwise rotationof rotor 13 through the piston 14 will move from a radial innermostposition to a radial outermost position as represented by the pusrtlonof the piston 18. As the rotor 13 rotates the piston 14 and all otherpistons in the motor bear on the inner race 32a of the anti-frictionbearing whichrotates therewith. The eccentric relationship of the rotor13 and the inner race 32a, however, causes a secondary relative movementof the pistons relative to the inner race, which relative movement inprior art devices has either occasioned excessive wear or requiredelaborate auxiliary anti-friction devices to compensate therefor.

As piston 14 is moving radially outward so also is the adjacent piston15 moving radially outward. Whereas the arcuate distance separating thepoint of contact of piston 14 with the reaction ring 32:: from the pointof contact of piston 15 with the reaction ring 32a is a minimum atapproximately the position shown in FIG. 2, this arcuate distanceincreases to a maximum when the pistons 14 and 15 would occupy theposition occupied by the pistons 18 and 19 respectively in FIG. 2. Thisincrease in the arcuate distance requires movement of the pistons 14 and15 relative to the inner race 32a.

Reference to FIG. 3 will clarify the above relative movement. The are DBin this figure represents the arcuate distance separating the points ofcontact of two adjacent pistons in any circular array when these pistonsoccupy their innermost radial positions. The are AB represents thearcuate distance separating the points of contact of these same twoadjacent pistons when they occupy their outermost radial positions. Thearcs AB and DE obviously have the same radius as they represent asegment of the inner race 32a, and the radial distance AD represents theamount of eccentricity between the axis of rotor 13 and the axis of theinner race 32a. Thus it will be seen that the arcuate separation of twoadjacent pistons will increase by the sum of lengths of the arcs AF andGB, or each piston will move with respect to the inner race a distanceequal to the arc AF or GB. It is this relative movement that produceswear. However, by providing a point of contact for each piston which iseccentric with respect to the axis of the piston the relative movementof each piston with respect to the inner race, as measured by are AF forexample, results in a force component which produces a rotation of thepiston on its own axis so as to castor, so to speak, causing the pointof contact of each piston to oscillate in a small are thus distributingthe wear over a larger area of the inner race.

The initial wear pattern produced by the foregoing action is shown inFIG. 4 by the series of arcuate darkened areas 32b, 32c, 32d whichrepresents the wear marks left by adjacent pistons on the surface of theinner race 32a after a brief interval of operation of the fluid motor.After prolonged operation of the motor the arcuate wear marks 32b, 32c,and 32d merge into a continuous band 32:: forming a wear pattern ofsubstantial area. This merging is probably explainable by differences inthe friction force between individual pistons and the reaction ringcausing the pistons to creep in gross with respect to the ring, or byshock produced within the motor in its usual application requiring rapidstarts, stops, and reversals in rotation.

By virtue of the foregoing structure, the need for elaborate auxiliaryanti-friction devices between the pistons and the reaction ring iscompletely obviated. Not only does this elimination of parts make for amore economical structure, but also it reduces the moment of inertia ofthe moving parts so as to permit of greater accelerations withoutdeleterious effect.

While there have been shown and described and pointed out thefundamental novel features of the invention as applied to a preferredembodiment, it will be understood that various omissions andsubstitutions andehanges in the form and details of the deviceillustrated and in its operation may be made by those skilled in theart, without departing from the spirit of the invention. It is theintention, therefore, to be limited only as indicated by the scope ofthe following claims.

What is claimed is:

1. In a rotary apparatus for operation with fluids, said apparatuscomprising a rotatable cylinder block having a plurality of slideablepistons disposed radially therein to define a plurality of variablevolume fluid chambers, valve means to expose each of said chambersalternately to high and low pressure conduits during rotation of saidcylinder block, and a reaction ring eccentrically disposed with respectto the axis of rotation of said cylinder block and co-acting with saidpistons to efiect radial movement thereof in timed relationship with theoperation of said valve means; the improvement comprising the saidpistons each having a substantially circular cylindrical configurationthe elements of the cylindrical surface thereof terminating in at leastone surface having a point thereof extending axially beyond all otherpoints in said surface the said point being eccentric to the axis ofrotation of said piston, and said reaction ring having a cylindricalinner surface in co-action with each of said points of said plurality ofpistons whereby during rotation'of said cylinder block the said pistonsare caused to oscillate upon their own respective axes to trace aplurality of contact paths on said reaction ring.

2. The improved structure of claim 1 wherein said one surface of saidpiston is a planar surface inclined at an angle less than a right anglemeasured with respect to the axis of rotation of said piston.

References Cited in the file of this patent UNITED STATES PATENTS1,673,514 Jernberg June 12, 1928 1,895,353 Sturm Jan. 24, 1933 2,292,181Tucker Aug. 4, 1942 2,359,513 Eden et al. Oct. 3, 1944 2,383,060 HoiferAug. 21,1945 2,454,418 Zimmermann Nov. 23, 1948 2,470,220 Mott May 17,1949 2,481,754 Johnson Sept. 13, 1949 2,736,267 Mosbacher Feb. 28, 1956FOREIGN PATENTS 7 737,584 Great Britain Sept. 28, 1955

